This invention relates to newly identified polynucleotides, polypeptides encoded by such polynucleotides, the use of such polynucleotides and polypeptides, as well as the production of such polynucleotides and polypeptides. More particularly, the polypeptide of the present invention has putatively been identified as human stanniocalcin-alpha. The invention also relates to inhibiting the action of such polypeptides.
Stanniocalcin (formerly known as both teleocalcin and hypocalcin) is an anti-hypercalcemic, glycoprotein hormone that is produced by the corpuscles of stannius, endocrine glands of the bony fishes. Humans also produce a stanniocalcin glycoprotein.
Stanniocalcin-alpha has similar reported biological activities to parathyroid hormone (PTH) and both of these proteins exhibit dual functions in mammals. They exert hypercalcemic activity possibly due to stimulation of bone resorption (Endocrinology 119:2249-2255 (1986)) and hypocalcaemic activity in fish. The hypocalcaemic activity is possibly due to inhibition of gill calcium influx (J. Exp. Biol., 140:199-208 (1988)). Further, PTH has a biphasic action on bone metabolism, i.e., at low doses it increases bone formation, while at high doses it increases bone resorption. Accordingly, both the polypeptide itself and an antagonist, under different circumstances, may be used to treat osteoporosis.
The Corpuscles of Stannius protein of non-humans has been studied extensively. Recently, a Corpuscles of Stannius protein has been purified and cloned from Anquilla australis. The kidneys of teleost fish have been found to contain secretory granules, the Corpuscles of Stannius. Electron microscopy indicates that the granules are of a proteinaceous nature and may represent hormones or enzymes of unrecognized physiological and biochemical function (Butkus, A. et al. Mol. Cell Endocrinol, 54:123-33 (1987)).
There has also been isolated and purified a glycoprotein from the Corpuscles of Stannius of trout, which is considered hypocalcin, the major hypocalcemic hormone of fish. This product is present in relatively large amounts in the Corpuscles of Stannius of several species (i.e., European eel, tilapia goldfish, and carp). Hypocalcin is typically released from the Corpuscles of Stannius in response to an experimentally induced increase of the blood calcium concentration. Ultrastructural observations show that after this treatment the hypocalcin-producing cell type of the corpuscles of stannius are almost completely degranulated. The isolated glycoprotein has an apparent molecular weight of 54 kDa. (Lafeber F. P. et al., Gen Comp. Endocrinol, 69:19-30 (1988)).
Moreover, it has recently been shown that several synthetic peptide fragments of teleocalcin inhibit calcium uptake in juvenile rainbow trout (Salmo Gairdneri). The N-terminal peptides (amino acids 1 to 20) of both eel and salmon teleocalcin significantly inhibit 45Ca uptake at the high point of the calcium uptake cycle (up to 75%), although the effective doses of the peptides on a molar basis were 20 to 200 times that of the intact molecule. In contrast, the C-terminal fragment of eel teleocalcin (amino acids 202 to 231) did not have an inhibitory effect on calcium uptake (Milliken C. E. et al., Gen. Comp. Endocrinol, 77:416-22 (1990)).
There has also been a description of the purification and characterization of two salmon stanniocalcins, and the examination of the regulation of hormone secretion in response to calcium using both in vitro and in vivo model systems. The molecular cloning and cDNA sequence analysis of a coho salmon stanniocalcin messenger RNA (mRNA) from a salmon CS lambda gt10 cDNA library is described. The stanniocalcin mRNA in salmon is approximately 2 kDa in length and encodes a primary translation product of 256 amino acids. The first 33 residues comprise the preprotein region of the hormone, whereas the remaining 223 residues make up the mature form of the hormone. (Wagner G. F. et al., Mol. Cell Endocrinol, 90:7-15 (1992)).
The polypeptide of the present invention has been putatively identified as human stanniocalcin-alpha. This identification has been made as a result of amino acid sequence homology.
In accordance with one aspect of the present invention, there is provided a novel putative mature polypeptide which is human stanniocalcin-alpha, as well as biologically active and diagnostically or therapeutically useful fragments, analogs and derivatives thereof.
In accordance with another aspect of the present invention, there are provided isolated nucleic acid molecules encoding human stanniocalcin-alpha, including mRNAs, DNAs, cDNAs, genomic DNA as well as antisense analogs thereof and biologically active and diagnostically or therapeutically useful fragments thereof.
In accordance with yet a further aspect of the present invention, there is provided a process for producing such polypeptide by recombinant techniques comprising culturing recombinant prokaryotic and/or eukaryotic host cells, containing a human stanniocalcin-alpha nucleic acid sequence, under conditions promoting expression of said protein and subsequent recovery of said protein.
In accordance with yet a further aspect of the present invention, there is provided a process for utilizing such polypeptide, or polynucleotide encoding such polypeptide, for therapeutic purposes, for example, to treat electrolyte disorders which lead to renal, and heart diseases and, due to a biphasic action of the polypeptide it may be employed to treat, osteoporosis, Paget""s Disease and osteopetrosis.
In accordance with yet a further aspect of the present invention, there are provided antibodies against such polypeptides.
In accordance with yet another aspect of the present invention, there are provided antagonists to such polypeptides, which may be used to inhibit the action of such polypeptides, for example, in the treatment of osteoporosis and hypocalcemia. Hypocalcemia can arise from a number of different causes including renal failure, hyperparathyroidism, severe infections, pancreatic insufficiency or burns which trap calcium from the intercellular fluid. Hypocalcemia results in tetany, convulsions and other related disorders.
In accordance with still another aspect of the present invention, there are provided nucleic acid probes comprising nucleic acid molecules of sufficient length to specifically hybridize to human stanniocalcin-alpha sequences.
These and other aspects of the present invention should be apparent to those skilled in the art from the teachings herein.